L\u00f4 \u0111\u1ec1 x\u1ed5 s\u1ed1 t\u1eeb x\u01b0a \u0111\u1ebfn nay lu\u00f4n \u0111\u01b0\u1ee3c coi l\u00e0 tr\u00f2 may r\u1ee7i. Ng\u01b0\u1eddi n\u00e0o may m\u1eafn l\u1eafm th\u00ec m\u1edbi tr\u00fang gi\u1ea3i \u0111\u1ed9c \u0111\u1eafc, kh\u00f4ng th\u00ec mua h\u00e0ng tr\u0103m l\u1ea7n ch\u1eb3ng l\u1ea5y 1 l\u1ea7n \u0111\u01b0\u1ee3c gi\u1ea3i an \u1ee7i. Nh\u01b0ng \u0111\u1ed1i v\u1edbi Stefan Mandel \u2013 m\u1ed9t nh\u00e0 kinh t\u1ebf ng\u01b0\u1eddi \u00dac th\u00ec kh\u00e1c, \u00f4ng c\u00f3 t\u1edbi 14 l\u1ea7n tr\u00fang s\u1ed1 nh\u1edd m\u1ed9t b\u00ed quy\u1ebft v\u00f4 c\u00f9ng \u0111\u1eb7c bi\u1ec7t.<\/p>\n
V\u00e0o nh\u1eefng n\u0103m 1960, l\u01b0\u01a1ng c\u1ee7a Mandel ch\u1ec9 c\u00f3 88 USD\/th\u00e1ng. Th\u1ea5y cu\u1ed9c s\u1ed1ng ngh\u00e8o kh\u00f3, l\u01b0\u01a1ng b\u00e8o b\u1ecdt \u00f4ng \u0111\u00e3 ngh\u0129 ra 1 c\u00e1ch ki\u1ebfm ti\u1ec1n kh\u00e1c \u0111\u00f3 l\u00e0 gi\u00e0nh nhi\u1ec1u th\u1eddi gian v\u00e0o nghi\u00ean c\u1ee9u lo\u1ea1i h\u00ecnh x\u1ed5 s\u1ed1. Cu\u1ed1i c\u00f9ng \u00f4ng \u0111\u00e3 \u0111\u01b0a ra thu\u1eadt to\u00e1n ch\u1ecdn s\u1ed1.<\/p>\n
V\u1edbi ph\u01b0\u01a1ng ph\u00e1p n\u00e0y \u00f4ng c\u00f3 th\u1ec3 d\u1ef1 \u0111o\u00e1n ch\u00ednh x\u00e1c \u0111\u01b0\u1ee3c 5\/6 s\u1ed1 tr\u00fang gi\u1ea3i. Sau \u0111\u00f3 \u00f4ng nh\u1edd b\u1ea1n b\u00e8 ng\u01b0\u1eddi th\u00e2n mua m\u1ed9t l\u01b0\u1ee3ng l\u1edbn v\u00e9 s\u1ed1 theo c\u00f4ng th\u1ee9c \u00f4ng t\u00ednh to\u00e1n. M\u1ed9t k\u1ebft qu\u1ea3 b\u1ea5t ng\u1edd \u00f4ng th\u1eafng gi\u1ea3i cao nh\u1ea5t.<\/p>\n